1. The Field of the Invention
The present invention relates to compositions and methods for whitening and desensitizing teeth. More particularly, the present invention encompasses compositions that include both a bleaching agent and a desensitizing agent. Such compositions are especially suitable for maximized tooth whitening and minimized tooth sensitivity when in prolonged contact with the teeth to be treated.
2. The Relevant Technology
The natural color of teeth is opaque to translucent white or slightly off-white. However, the use of certain foods and tobacco, the process of aging, diseases, trauma, medications, some congenital conditions, and environmental effects can cause teeth to become discolored. Because whiter teeth are considered to be aesthetically superior to stained or discolored teeth, there has been a large demand for dental bleaching compositions.
Typical tooth bleaching agents release active oxygen radicals. Such bleaching agents include peroxides, such as hydrogen peroxide, percarbonates and perborates of the alkali and alkaline earth metals, or complex compounds containing hydrogen peroxide. Also, peroxide salts of the alkali or alkaline earth metals and peroxyacetic acid (CH3C═OO—OH) are known to be useful in whitening teeth.
The most commonly used dental bleaching agent is carbamide peroxide (CO(NH2)2.H2O2), also called urea hydrogen peroxide, hydrogen peroxide carbamide, and perhydrol-urea. Carbamide peroxide has been used by dental clinicians for several decades as an oral antiseptic. Tooth bleaching was an observed side effect of extended contact time. Over-the-counter compositions of 10% carbamide peroxide are available as GLY-OXIDE® by Marion Laboratories and PROXIGEL® by Reed and Carnrick. A sticky bleaching gel which is able to hold a comfortable-fitting dental tray in position for an extended time period is available under the trademark OPALESCENCE® from Ultradent Products, Inc. in South Jordan, Utah.
Patients who have desired to have their teeth whitened have typically done so by applying a bleaching composition to the teeth by means of a dental tray for repeated treatments, or they have had to submit to conventional in-office bleaching techniques that required from 4 to 10 visits to the dental office before clinically significant results were achieved. Clinically significant results are quantifiable such as by measuring gray scale, L*, and as to yellowness or blueness, b*, in the CIE® system of color measurement or by equivalent methods.
Although dental bleaching compositions are effective in removing stains and superficial discoloration, they are often limited by the inherent translucence of many people's teeth. More precisely, teeth having more translucent enamel are difficult to whiten beyond a certain point since the yellowish or grayish tint of the underlying dentin is difficult to change by bleaching alone.
Another downside of tooth bleaching regimens is the tendency of tooth bleaching agents to cause increased sensitivity when applied to teeth over prolonged periods of time. Thus, attempts to further whiten a person's teeth, including prolonged bleaching of excessively translucent teeth, may result in increased tooth sensitivity, which can become quite severe for some people.
From the foregoing, it will be appreciated that what is needed in the art are improved compositions and methods for whitening teeth.
It will also be appreciated that what is also needed are improved compositions and methods for whitening teeth which reduce tooth sensitivity, compared to conventional dental bleaching compositions.
Such compositions and methods for bleaching and whitening teeth, while reducing tooth sensitivity, are disclosed and claimed herein.